Slagging is a problem frequently encountered in combustion chambers, particularly those used for the combustion of combustible gases containing entrained slag-forming particulates, such as for example, the afterburners employed in incineration plants or pyrolysis plants to complete the combustion of gaseous carbonaceous materials. Much of the particulate slag forming material is trapped in the combustion chamber as a molten slag. Tap-holes are provided in the combustion chamber for removing the molten slag. Horizontally disposed, frequently cylindrical, combustion chambers are normally disposed such that the bottom is slightly inclined and a tap-hole is provided in the bottom at the lowest end.
Frequently, highly viscous molten slags do not drain properly out of the combustion chamber through the tap-hole because without special precautions the molten slag drains as a relatively slow-moving thin film of molten slag over a wide path along or around the periphery of the tap-hole. Even a slight cooling as the thin slag film enters the tap-hole increases the viscosity sufficiently to start slag buildup on the wall of the tap-hole which in a short time bridges across the tap-hole opening, resulting in pluggage and inability to remove the molten slag in the combustion chamber, and necessitating a costly shut-down to chip away the solidified slag from not only the tap-hole but inside the combustion chamber where the slag has backed up.